(Updated: 20th May 2000)
Disordered Materials

Core Researchers:

Collaborating Researchers:

  • Mr. P. Behrenbruch, BHP Petroleum
  • Prof. S.F. Cox, Geology
  • Assoc. Prof. P. Evans, Forestry
  • Prof. W.B. Lindquist, Applied Maths, SUNY Stony Brook
  • Dr. M.B. Lyne, International Paper
  • Dr. K. Mecke, Physics, Univ. of Wuppertal
  • Dr. L. Paterson, CSIRO Petroleum
  • Prof. M. Sahimi, Chemical Engineering, Univ. of Southern California

Students:

  • Mr. C. Arns (UNSW)
  • Ms. L. Knuefing (joint with U. of Wuppertal, Germany)
  • Ms. J. Y. Lee (UNSW)
  • Ms. J. Liu (UNSW)
  • Mr. R. Roberts, Forestry and Carter-Holt Harvey
  • Mr. M. Saadatfar

Former Students:

Current projects include:

Development of efficient three-phase flow simulator

Direct and Stochastic generation of network models from tomographic images

Universality class of Invasion percolation

Impact of correlations on percolation properties/residual saturations

Percolation on Extended Grids

Stucture-property correlation

Droplet Penetration into porous networks: Role of Pore morphology

Characterisation of disordered media: Integral geometric measures

Generation of anisotropic model materials: Polymer blend morphology

Image Analysis of Data Sets

Project Summary

How do we describe and compare structures of complex - often disordered - materials? How does oil, water, gas, or nuclear waste flow through porous rocks? Why does ink-jet printing give clear and sharp lines on some papers, while it smudges on others. These questions are of enormous interest to both the pure scientific and the industrial communities. In the petroleum industry in excess of a billion dollars a year is spent laboratory measurements on core materials. To date, there is little basic science to support the interpretation of data. A major shortcoming in the understanding of processes involving complex porous and composite materials has been the inability to accurately characterise the microstructure. Successful predictive modelling of the properties of ``real world'' materials is reliant on this accurate characterisation. Our group is addressing these issues with a combination of theoretical, computational and experimental skills.

The objective behind the Disordered mesoscale physics programme is to bring the tools of physics and mathematics to bear on these problems which are the concern of engineers, geologists and forestry researchers. The recent significant award of an internal ANU PPF grant will ensure that we can build on our theoretical understanding and remain in the forefront of this development. We have also received an award from the federal Research Infrastructure scheme to build a High-resolution X-ray CT (Computed Tomography) facility to experimentally characterise the morphology of complex materials and visualise multiple fluid phases in porous materials. This experimental facility will provide us with a rich source of data for the goals of our research. We have also been very successful in leveraging funding from government and industrial sources for specific applied projects.

The state-of-the art CT facility will be able to generate images of up to 40963 at resolutions of less than 5 microns. We, along with collaborators are developing software tools to analyse these images and modelling the material properties. Given the speed of acquisition of the facility and the size of the individual data sets (up to 128 Gbytes), we need to analyse the data at speeds comparable to experimental acquisition. Much of our current focus is on the computational areas of image analysis and reconstruction, parallelisation and in software development for computational physics.  

Figure 1: Setup for 4th generation X-ray CT with cone-shaped X-ray beam.

The development of a facilty which can acquire images, perform geometric analysis, visualise and calculate flow and material properties within a day will have a major impact on our goal to catalogue material structure and understand physical properties from structural characteristics. The project is a significant user of High-performance computing facilities at the A.N.U. and will give researchers in various scientific and industrial applications the ability to study complex materials in a virtual environment.


Fundamental Research

  • Quantifying Disordered Morphologies The ability to generate non-destructive 3D images will allow us to catalouge the detailed microstructure of a range of complex materials. The question remains; how can one describe these forms of arbitrary shape? We need to quantify random morphologies obtained experimentally from the micro-CT (see Fig. 2) facility utilising tools from integral, statistical and differential geometry and topology and generate a complete inventory of forms using these techniques.

  • Figure 2: Images of real materials from tomography across a range of length scales. At the cm scale, (a) A termite nest: at the 10 mm scale, the pore space of (b) a Berea sandstone at 10 microns, and (c) the calcitic skeleton of a sea urchin.

  • Characterization for multiphase flow studies: Generating equivalent network structures The availability of direct measurements of the pore space of sedimentary rocks in 3D has required the development of computational tools to directly measure the stochastic nature of the void space and to construct realistic network representations of the complex space. We need to generate stochastic networks with topological properties representative of real sedimentary rocks and measure and quantify pore geometry and correlations that occur at the pore scale in sedimentary rocks.
  • Stucture-property correlation: Correlating the macroscopic properties of disordered materials to their microstructure, engineers rely on simple empirical models that ignore all microstructural information. The bulk of the experimental and theoretical work has been devoted to establishing the empirical coefficients for each class of material. Imaging materials via high-resolution X-ray CT and subsequent laboratory measurement of material properties will help us form a more accurate and comprehensive picture of the role of microstructure in governing the mechanical and transport properties of disordered materials. The longer term aim is to offer researchers the ability to study a range of properties of complex materials in a virtual environment.
  • Image Analysis of Data Sets: High resolution X-ray CT facility will allow us to produce non-destructive 3D images of complex materials. Unfortunately, imaging properties of the specific apparatus can give rise to distortions which can hamper the quantitative analysis of structure. We need to consider different inversion strategies used to restore images and compare their efficacy. This work will provide crucial input to the interpretation of the 3D images obtained at our CT facility and complimentary laser confocal microscopy facilities.


Applied Research

  • Petroleum production: Worldwide, the petroleum industry spends in excess of a billion dollars annually on work related to the characterisation of reservoirs. A large part of this is spent on obtaining core material, performing tests and measurements on the core material and interpreting the test measurements in order to apply them to the field scale. Billion dollar field development decisions are made on the basis of these interpretations. A major uncertainty in the interpretations is the manner in which measurements on the core-scale relate to the field scale. This is closely related to the nature of heterogeneity from the field-scale down to the pore-scale. Although reliable techniques are available to characterise heterogeneity on the larger scales, very little is known of the nature of heterogeneity on the core to pore scales. The interpretation and application of measurements on the core-scale to the field-scale is responsible for the introduction of major levels of uncertainty in field development decisions. A significant reduction in this level of uncertainty would have a major beneficial effect on the economics of future field developments and would make the Australian oil and gas industry more competitive internationally. The Australian oil and gas industry is currently anticipating major offshore developments in the Timor Sea. High development costs will make many of these developments marginal. A single incorrect development decision could result in losses of the order of hundreds of million dollars

    Despite the large amounts spent on the measurements, there is little basic science to support the interpretation of data. The ability to image, visualise and model laboratory core measurements will potentially enhance interpretation of laboratory measurements. Modest improvements would significantly reduce the economic risk associated with new oil and gas developments and have a major impact on the petroleum industry. This work is being undertaken in collaboration with BHP Petroleum.

  • Paper manufacture: The development of improved printing mediums and technologies depend on an understanding of how a complex material made up of cellulose fibre matrix, often coated with a consolidated mass of pigment and binder can be modified to improve printability, durability and appearance. To understand the flow, optical and mechanical properties of paper products one must develop a realistic structural description of the pore space coupled with an ability to simulate flow and mechanical properties on massive three-dimensional grids. This work is in collaboration with R. Roberts at Carter-Holt Harvey and M.B. Lyne at International Paper.
  • Crustal Geophysics Within the Earth's crust, fluid flow in fractured rock masses influences a range of important geological processes, but particularly the genesis of many types of precious metal and base metal ore deposits and hydrocarbon migration in some reservoir types. A rigorous understanding of fracture-controlled fluid migration is also required to develop more effective strategies for the sustainable development of geothermal energy resources and for the analysis of risk associated with toxic waste (both nuclear and chemical) containment in deep underground repositories. High-resolution CT techniques will image in 3D the growth of fracture networks produced by deformation. These experimental results, together with the proposed computational modelling studies will allow development of theoretical models describing the relationships between disordered fracture networks and fluid transport properties. This research effort is headed by Prof. S.F. Cox, Geology Department.